1972 K20 Super Cheyenne - Modernized Classic

[Farm Shop]

I'll start off with some history of this truck: My older brother, Chad, bought his 1972 Cheyenne Super K20 in Wyoming in 1999 when he was 16 while on our family summer vacation out west. Long story short, it was sitting by the road at a small dealership, our dad made a deal on the spot, and we drove it 1500 miles home.

As far as we know, it is a factory K20 Super with a shortened frame and factory short bed. It has a 1965 passenger car 396, SM465 4 spd, and NP205. Since Chad has owned it, he's rebuild the front hubs, replaced small things as needed, new 35" MT's, and rebuilt the 396 top to bottom in 2003. Unfortunately, until this past summer, life has gotten in the way and the truck has only been driven about 2000 miles in the last 8 years.

That brings us up to this summer. Chad was finally able to fair weather daily drive the '72 all summer, and even do a leg of Hot Rod Power Tour. He got along well, but no electric choke, a torn accelerator pump boot, squealing v-belt, and no overdrive became bigger annoyances than they had been in the past. We've discussed options like an EFI 6.0 LS and 4L80e swap, maybe drop in a 1996+ Vortec 454, or even a Holley EFI on the current BBC. After a lot of deliberation, we decided to EFI the current 396 since we know its a strong engine, it matches the DNA of the truck, and in an "LS THE WORLD!!" environment, the BBC is a welcome site.

The requirements for this winter are:
- Convert the 396 to EFI
- Overdrive manual trans
- Keep 4x4 functional
- Serpentine accessories

This project will start some time in December, and right now we are still collecting parts. So far we have:
- 1996 NV4500 4x4 5 spd trans
- 1996 serpentine accessories off a 350
- NP208 transfer case
- Holley MPFI intake and throttlebody
- Walbro in-line 255lb/hr fuel pump, lines, filters, etc
- A good friend that is a lot smarter than we are is currently configuring the Mega Squirt MS2 ECU.
- Donor EFI harness from a 2008 LS4 Impala that I will use to build the MS2 harness

I will keep this thread updated in real time as we start turning wrenches in a few weeks. In the mean time, here are a few pics of the truck and parts we've accumulated and will be using.





Ready for HRPT 2015:







Bringing home the trans donor:


I had some excitement bringing the parts truck home. . .

[bowtieguy79]

Can't wait to see this one in progress and done.

Hope you get the trailer fixed soon, wow I'll bet that made some noise!

[jhama78]

Cool truck, subscribed for updates, especially the MS EFI conversion.

[cooperhw]

sweet truck and great plans.

[Bishops Trucks]

I'll be keeping an eye on this one. Nice truck to start with. Is that your "Judge" beside it?

[Farm Shop]

Originally Posted by Bishops Trucks

Nice truck to start with. Is that your "Judge" beside it?

Thank you. We could get by with a $25 carb rebuild and keep going with it as-is, but what fun is status quo??

Yep, its a legit, documented Judge. I did a heads/cam/stall LS1/4L60e swap winter 2012/2013 and love everything about it compared to the carb'd 400/400 combo.

Here's my build thread on the local forum: http://properimage.net/showthread.php?t=1227

[swamp rat]

Subscribed!

[redbaron]

Cool truck and story. I'm in.

[Farm Shop]

Small update. We dropped the trans/transfer case out of the '96 dually parts donor but then ended up locally selling the rest of the complete truck... including the serp accessories we planned to use on Chad's project. Luckily, I found a guy within driving distance parting a 1990 2500 Chevy after the TBI 454 spun a rod bearing. We may come up with simpler/cleaner custom design down the road, but for now this will be a nice improvement and easily fit within the budget... and it has a brand new alternator to boot!






The next step is to give the NV4500 and NP241 a thorough cleaning. After that, we'll drop the 465/205 out of the '72 and assess our options. That brings me to a question for the experts:

What combination of clutch parts will work "best" for this build? Here is what I'm working with:
- 1965 396 with a decent clutch for the SM465
- 1996 NV4500 and smoked stock clutch
- ***We are keeping the OE 1996 hydraulic clutch***
- I kept the starter from the 1996 350 with hopes to use it on the 396

Will the NV4500 work with the current 396 flywheel/clutch? I haven't counted the 396 ring gear teeth yet, but what are the chances the 350 starter will work with the current 396 flywheel?

Or, would a stock replacement clutch for the 1996 NV4500 bolt up to the 396 flywheel?

Or, if I bought a clutch for the 1996 truck, would that 350 flywheel bolt onto the 396? (pretty sure that's not an option)

I appreciate any insight... I haven't been able to find anyone with my exact build (most use the aftermarket BH to retain the manual clutch), and trying to piece information together here and there is making my head spin.

[notchbackgta]

The GM NV4500 uses a 10 spline input, I just used the same one that was on the tired old 307 on the back of the BBC. It is a little weak for the BBC and it slips a little if I really get on it

[Farm Shop]

Between winter storms, power outages, holidays, and sick kids we finally got to wrench on the '72 a couple days this week. First thing was to pull out the seats and carpet to remove the transmission hump.

We knew the rockers and cab corners had been replaced at one time (at least 20+) years ago, as well as a couple small patches on the driver floor. The truck is showing its age, but still very solid, and the weaker spots haven't gotten much worse over the last 15 years.

Pulling the factory buckets out.


The black carpet has almost no wear, but has faded bad enough to be replaced.





This year we are trying to focus strictly on mechanical updates, but we can't ignore the rust scale on the floors. The truck will get a frame-off in a few years, so for now we'll wire-wheel the rust and slow it down with some POR-15. The driver side has the most damage.









Up to now I had thought the replacement rockers and cab corners were not perfect, but done fairly well.




And then I saw this, which will be addressed in a few years. . .



Once the trans hump was out, we dropped the transfer case and then the trans. We also decided to pull the 396. This is a good time to replace a weeping block heater, replace the leaky and very cheesy chrome oil pan, and do a cosmetic refresh on the engine and clean the engine bay. It will also make building the EFI wire harness a LOT easier with the engine on the floor instead of in the truck.





Working on a lifted truck was great until the cherry picker wouldn't get the engine over the core support. Letting some air out of the tires got us just low enough to clear.


And then moved the truck to the cold side of the shop.


That's all the further we got so far. Next up is cleaning the "new" trans/TC, and clean/paint the engine.

[flashed]

That is a very nice truck ,just saw one here last night very similar to it driving around ,never seen it before .

[Nitis]

Sweet rig for sure really makes a guy wonder how it started life if it was a swb with 8 lugs and big block swapped in swapped in a 2wd or what but it sure is pretty!

Just a thought cause you mentioned some stuff about the EFI that is way over my head but have you looked into the FItech stuff? They are turning out some nice affordable stand alone products that sound much more simple than what you mentioned. Just a thought good luck

[Ol Blue K20]

I'm in to watch...nice truck and curious about the injection and how your going to like it.

[Voodoo556]

That thing is a beauty! Nice rig!!!

[Farm Shop]

Originally Posted by Nitis

Sweet rig for sure really makes a guy wonder how it started life if it was a swb with 8 lugs and big block swapped in swapped in a 2wd or what but it sure is pretty!

We've wondered the same thing for years, but we're pretty confident that the cab, chassis, and front sheetmetal all belong together and are original 1972 K20 Cheyenne Super. The 396 is out of a 1965 passenger car (first year of the 396, so probably an Impala), and the bed was probably sourced from a salvage yard back in the day. I just noticed after 15 years that the bed trim is actually long bed pieces that had been shortened to match the bed. No clue about the SM465, but that doesn't really matter any more, lol.

Originally Posted by Nitis

Just a thought cause you mentioned some stuff about the EFI that is way over my head but have you looked into the FItech stuff? They are turning out some nice affordable stand alone products that sound much more simple than what you mentioned. Just a thought good luck

I have not looked into them, but at a quick glance they do seem to be worth a closer look, but we are set on using the Mega Squirt MS2 for this truck. We also really wanted multi-port EFI for form as much function.

My buddy actually just built the MS2 board and dropped it off last week. With a blank harness bundle and tossing him a few bucks to assemble the board, the ECU will be under $400. The original goal was to have a complete MPFI EFI conversion for under $1000, but it looks like we'll end up being closer to $1200 after fuel system, WBo2, and injectors. Granted, this is with finding deals and utilizing used/salvage yard components, so that plays into the low-ish cost.

After exposure to several different EFI platforms (EFI Live and HPT for stock GM, Holley Dominator, and Mega Squirt), I really like the MS user interface. An added bonus is Bluetooth capability. We'll set up the truck with a laptop, and then be able to fine tune in real time off our phones or tablets. I still have a lot to learn, and the best way to learn is by hands-on experience, so I'm really excited to get this rig fired up.

[1970ChevyChamp]

Subscribed on this one. I'm in the process of doing a frame off restoration of a '67 swb with a '71 K20 chassis underneath it. Just got the frame shortened down and now in the process of collecting parts to start putting it all back together. I hope my finished product looks half as good as this rig! Good luck with your upgrades, keep us posted!

[Farm Shop]

I ran into some fitment issues this weekend. This is my original post in the 4x4 section:

I could really use some insight as to what I am doing wrong here. I did a TON of reading on here, pirate4x4, etc, and thought I had all my ducks in a row, but apparently not.

I'm swapping out the SM465/NP205 in my brother's '72 K20 for an NV4500 from a 1996 GMC 1 ton. I got a 32 spline NP208 transfer case since everything I read said it would bolt right up to the NV. Long story short, it doesn't.

Please excuse the nastiness, I was just trying to verify fitment of everything before cleaning and painting.


Output shaft of NV4500


NP208




When I install the TC to the trans, this is all the further it will slide into place


After some measuring and head scratching, I put blue marker on the aluminum casting of the 208 and verified that the portion of the input shaft bearing support contacts the large damper on the output shaft, keeping it from fully seating. You can see where the marker is rubbed off due to contacting the damper in the trans.


Where did I go wrong? Thanks in advance for any help or recommendations on where to go from here.

[Farm Shop]

So after some more digging, it seems like this trans is a bit of an odd duck. The damper (big steel drum counterweight) apparently started in 1995 behind the 6.5 diesel to fix the 5th gear nut loosening issue associated with the hammering harmonics of a lugging diesel. The weird thing is that this truck has a vortec 350... but it was a 1 ton dually, so maybe all 1 tons got the same trans?

I don't know. Regardless, the damper has to come off. Behind a mild big block that won't ever tow much to be a problem, eliminating it shouldn't be an issue. Now I just need to find a trans shop with the correct spanner/socket to do it for me... spending $170 on a production socket is not a great option right now!

[Captainfab]

I have seen the damper on the output of a 2wd NV4500. Is your trans a 2wd or a 4wd trans?

[Farm Shop]

Originally Posted by Captainfab

I have seen the damper on the output of a 2wd NV4500. Is your trans a 2wd or a 4wd trans?

Its out of a 1996 GMC 3500 dually 4x4 with a 350 gas.

[Farm Shop]

This project has been moving slower than expected/planned. Between all the NV4500 fit up issues, and now realizing the mainshaft is smoked requiring a full rebuild, we have gotten very discouraged.

The other issue has been time... my brother and I don't have much to spare, let alone spare time that lands at the same time. Soooo, this project is going to move a lot slower than expected, but the goal is still to have it running this summer.

There has been some positive movement thought. Chad pressure washed and wiped the engine down with acetone, then got a fresh coat of Chevy orange on the block. We set the intake in place for some positive reinforcement.

[jeh]

Good looking truck you have there. I'll follow along also to see the fuel injection setup!!! It will be a cool ride when you get done, just have some patience and everything will come together. All of us have stumbling blocks at times that get in our way, hang in there